Doctors and nurses didn't believe Tomisa Starr was having trouble breathing.
Two years ago, Starr, 61, of Sacramento, Calif., was hospitalized with elevated blood pressure. She suffers from multiple chronic health conditions, including heart failure, and uses an oxygen tank at home.
But Starr said her request for supplemental oxygen while hospitalized was denied because a pulse oximeter reading on her finger incorrectly indicated she was getting enough air on her own.
Starr, who is Black, told the nursing team that research shows that devices that measure oxygen levels in the blood may not work as well on people with darker skin tones and may make these patients appear healthier than they actually are.
Starr said the response was shocking.
"Providers demand to know, 'Who told you that?'" she said. "I'm in the hospital and I have to defend myself just like I would in court."
Starr said doctors' suspicion that black Americans may have faulty pulse oximeter readings is not unique.
"I've been giving presentations about this to doctors who should know about this study, and they're always shocked," said Dr. Hugh Cassil, a critical care physician at South Shore University Hospital in New York. "This device has inherent racial disparities. , has been ignored for years.” Cassiere also leads an independent expert committee formed by the FDA to study the pulse oximetry issue.
Potential problems with measurement equipment have been known for decades. The FDA began developing guidance for manufacturers to address these issues in 2013, but has taken little action since.
It wasn’t until the pandemic that the real dangers faced by Black patients became clear. In 2021, the U.S. Food and Drug Administration warned of flaws in pulse oximeter readings on dark-skinned people.
Last week, the FDA issued draft guidance requiring manufacturers to significantly expand the range of skin tones when testing their devices and show that they work equally well for all skin pigments.
Historically, companies have not been required to include large numbers of dark-skinned people in pulse oximetry studies.
"Frankly, we're not measuring it consistently and we're not measuring it in a very efficient or systematic way," Dr. Michelle Tarver, director of the FDA's Center for Devices and Radiological Health, told NBC News. ." Draft guidance has been released.
Cassier expressed support for the new recommendations. "This is several years ahead of the 2013 guidelines," he said.
The U.S. Food and Drug Administration does not approve or authorize all pulse oximeters on the market. The FDA said "general health" devices marketed to hikers, cyclists or other athletes who might want to estimate blood oxygen levels are not regulated and should never be used to diagnose or monitor health problems.
Pulse oximeters used exclusively for medical purposes do fall under the jurisdiction of the FDA. It's these device manufacturers that the agency's draft guidance targets.
The gold standard and most accurate way to test whether a person's oxygen levels are normal is to insert a needle into a person's wrist and draw blood.
So-called arterial blood draws are invasive and painful. But it also gives doctors important clues about how well a patient's lungs are functioning, providing insight into which patients should be hospitalized and receive supplemental oxygen or other treatments.
Pulse oximeters emerged in the 1980s as a simple, painless alternative. The device emits light through your fingertips to search for oxygen-rich blood. In theory, the more light absorbed, the better.
But this light is also absorbed by melanin, or pigment, in the skin. As a result, black and brown people are more likely to get pulse oximeter readings that show their blood oxygen saturation is higher than it actually is. That is, they may still be having difficulty breathing despite normal pulse oximeter results.
A study published 34 years ago was the first to reveal possible racial differences in pulse oximetry. "This should be of concern to the FDA," Cassier said.
It has been largely ignored.
“I attended medical school at Howard University, which is a historically black university, and this has never come up—never in training, never in practice,” said founder of Roots Community Health said Dr. Noha Aboelata, People and Chief Operating Officer. Oakland, California. “I didn’t know anything about it until the first year of the pandemic.”
In 2020, Dr. Thomas Valley and his colleagues at the University of Michigan reignited rumors about this disparity as they were overwhelmed with COVID-19 patients. The vast majority of the sickest patients are black.
"We started noticing that the numbers on the pulse oximeter screen didn't match the numbers we were seeing in the arterial blood," Valli said. "We went from room to room and the numbers didn't look right."
The team believes this is an anomaly caused by the new coronavirus - a completely new virus the world has never seen before.
“It wasn’t until a few months later that the lightbulb went off,” Valli said. "This is not a COVID issue. This is a 'color' issue."
His team published findings on racial bias in pulse oximeter readings in December 2020. It was this study, published in the prestigious New England Journal of Medicine, that Starr used to alert her doctors.
While there is no direct link between false pulse oximeter readings and COVID-19 deaths, more studies have found that people of color are more likely to die from COVID-19 than white people.
The stark differences extend beyond COVID-19 treatments.
Wrong pulse oximeter readings in patients of color "could prevent Black patients from being candidates for advanced treatments like heart pumps or heart transplants," said Sarah Adey, associate director for innovation at the Frankel Cardiovascular Center at University of Michigan Health. She was a co-author of a study published in 2024 that found unreliable pulse oximeter readings may limit the eligibility of Black patients with heart failure to undergo these potentially life-saving procedures.
Valley published additional research that found most pulse oximetry studies show bias against people with darker skin tones.
"The question everyone wants to know now is: Which devices are equally effective regardless of skin color?" said Dr. Michael Lipnick, an anesthesiologist at the University of California, San Francisco. His team is analyzing results from more than 50 pulse oximeters to try to answer that question.
Under careful observation, UCSF researchers installed various pulse oximeters to study participants' fingers, then lowered their oxygen levels to the point where the devices should signal a problem.
They expect some devices, perhaps cheaper ones, to have poor overall performance.
This is not necessarily the case. "The performance of some devices is independent of skin pigment, while others are not," Lipnick said. "We don't understand why."
A measure of how well oxygen-rich blood is circulating in a person's body, called perfusion, may also come into play. This is not a skin color specific condition. It will likely take years for the team to understand the differences in pulse oximeter readings and why some perform poorly on people of color.
For doctors who primarily treat Black patients, the delay in providing answers or taking action is uncomfortable.
"We thought there was going to be some kind of drastic action," said Aboelata of Oakland's Roots Community Health Center. “Given the diversity of our country, how could we possibly have a medical device that only works on white skin?”
Roots Clinic has sued 13 companies that manufacture or sell pulse oximeters.
So far, Medtronic has agreed to warn California hospitals that its devices may provide higher readings for patients with darker skin. Four companies, including Veridian Healthcare, Compass Health Brands, Gurin Products and Zewa, have agreed to add warning labels for California consumers.
But patients like Starr still rely on pulse oximeters because they know they can provide erroneous results. She said she had no other choice. "They're all I have."